Wall structure for regeneratively cooled rocket motors



1954 D. B. ROSSHEIM ET AL ,6 9, 5

WALL STRUCTURE FOR REGENERATIVELY COOLED ROCKET MOTORS Filed March 4, 1949 IN V EN TORS DAVID B- AS V. D CABE EQON A SIE 5y 4'',

A TTOR/VEK Patented Feb. 23, 1954 WALL STRUCTURE FOR REGENERATIVELY COOLED ROCKET MOTORS David B. Rossheim, Teaneck, and Douglas V. Doane, Maywood, N. .l., and Carleton A. Siemer, Staten Island, N. Y assignors to The M. W. Kellogg Company, Jersey City, N. 1., a corporation of Delaware Application March 4, 1949, Serial No. 79,562

7 Claims. 1

The present invention relates to thrust cylinders for rocket motors and more particularly to a regeneratively cooled rocket motor thrust cylinder capable of operating continuously over extended periods of time.

Heretofore, attempts to operate large rocket motors using a liquid propellant continuously over extended periods of time have been unsuccessful, due primarily to the fact that it has not been possible to maintain the temperature of the rocket motor thrust cylinder and its associated thrust nozzle below their melting points. As a result it has been necessary to shut such rocket motors down after a short burst, to prevent the thrust cylinder and nozzle from being eroded or burned up. Attempts have been made to cool the thrust cylinder, but heretofore these attempts have been unsuccessful. Attempts to utilize a separate coolant add to the rocket motor the weight and bulk of the coolant, the means provided for its storage, and the associated valves, piping and pumps necessary to circulate it. All of this is obviously undesirable, and especially so in rocket motors intended for airborne application. In addition to the above disadvantages the use of a separate coolant reduces the efficiency of the rocket motor by reason of the heat lost to the coolant.

Attempts, prior to the present invention, at

regenerative cooling of rocket motors employing fluid propellants, wherein the fluid propellant is employed as a coolant, have also been unsuccessful due to the problem presented by the great amount of heat that must be dissipated and the relatively small amount of coolant that is available to dissipate it.

It is one object of the present invention to provide rocket thrust cylinder capable of operatin? continuously over extended periods of time.

It is another object of the present invention provide a regeneratively cooled rocket thrust cylinder capable of operating continuously over extended periods of time.

It another object of the present invention to provide a light Weight regeneratively cooled rocket thrust cylinder capable of operating continuously over extended periods of time.

It another object of the present invention to provide light weight regeneratively cooled rocket thrust cylinder capable of operating con-- tinuousl'y over extended periods of time and having sumcient strength to resist collapsing due to the pressure of the coolant fluid.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

The invention accordingly comprises an apparatus possessing the construction, combination of elements and arrangements of parts which are exemplified in the following detailed disclosure and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawing wherein;

l is a somewhat diagrammatic plan view, partly in section, of a rocket motor thrust cylinder embodying the present invention;

2 is an enlarged fragmentary sectional view taken along the line 2-2 of Fig. 1;

Fig. 3 is an enlarged fragmentary sectional view of the coolant inlet manifold of the thrust cylinder of Fig. l;

Fig. 4 is a diagrammatic view of a rocket motor incorporating the present invention; and

Fig. 5 is a view similar to Fig. 2 but showinga modification thereof.

The present invention comprises a rocket motor thrust cylinder having an inner shell and an outer shell concentric therewith and spaced therefrom a predetermined distance to give an annular coolant passage around the inner shell, and extending substantially along its entire length, having a cross sectional area such that the rate of flow of the coolant, which is one of the propellants, will give a film coefficient of heat transfer such that the limited flow of coolant available will maintain the inner shell below a predetermined temperature. A further feature of the present invention. is the manner in which the inner shell and outer shell are attached to one another to space said shells a predetermined distance apart and maintain the concentricity of the shells under all operating conditions, and to reinforce the inner shell against collapsing under the pressure of the coolant at the high temperature the inne shell attains incontinuous operation, and at the same time not seriously interfere with the transfer of heat from the inner shell to the coolant, or with the flow of said coolant through said passage.

As stated above the amount of propellant that is used is extremely small in proportion to the amount of heat that is generated. Prior art regeneratively cooled thrust cylinders have failed because the limited amount of propellant available was not employed effectively, and as employed was not sufficient to cool the thrustcylinder and maintain its temperature low enough to prevent its destruction. Another cause of failure in prior art regeneratively cooled thrust cylinders has been the relatively thick wall of the thrust cylinder which had heretofore been necessary to withstand the high pressure of the propellantcoolant needed to properly inject the propellant into the thrust cylinder. I-Ieretofore, when the thrust cylinder wall had sufficient strength to withstand the pressure of the propellant-coolant, it was too thick to permit heat transfer through said wall at a rate high enough to prevent its destruction by burning. When the prior art thrust cylinders were made with a Wall thin enough to permit effective heat transfer therethrough, they failed in operation by collapsing under the pressure of the propellant-coolant.

The present invention overcomes all of the above objectionable features of the prior art thrust cylinders and provides'a light weight regeneratively cooled thrust cylinder having relatively thin walls that are so constructed and arranged that they'are capableof withstanding the high operating pressure of the propellantcoolant when they attain their operating temperature to permitthe effectivetransfer of heat through the inner shell thereof. The annular passage for the propellant-coolant is so constructed and arrangedthat said coolant-is forced to travel through said passage at a high velocity and thus has a high film coeflicient of heat transfer. Such a structuremakes possible a high rate of heat transfer through the thrust cylinder wall to the coolant whereby a relatively small volume of coolant is capable of effectively main taining the temperatureofthe thrust cylinder at a safe level and the thrust cylinder can be operated continuously over extended periods of time.

Referring now to Fig. 1 of the-drawing, there is disclosed a preferredembodiment of the present invention comprising .a rocket motorthrustcylinder having an inner shell l fabricated from sections Ina, I02), I00, and d Section la is substantially cylindricalin cross section, section 10b and 10d are conicaland section I 00 is a portionof a torus. Adjacent edges of sections r [0a, I01), I00, and 10d arev substantially the same diameter and are. welded together. In thev completed inner shell), section 10! definesa combustion portion and sections 101), IOc-and 10d form a Venturi type'thrust nozzle. Sections 10a, lflb, I00 and l0d are disclosed as being formed from plate or sheet material cut to the desired dimensions, bent to shape, and. then welded together. Obviously, innershell [0 can be formed from a single sheet of material, from a greater or lesser number of sections,- or can be constructed in any other desired 'manner. Section. .100 is preferably formed'from thinner material than the other three sections for reasons that will be explained more fully hereinafter. l

Inner shell I 0 is enclosed in and concentrically spaced a predetermined radial distance from an outer shell 42 made up ofsection's 12a, I26, I20 and [211, each of which is generally similar to" sections Illa, [0b, Hlc'andllld of inner shell Ill-andwhich are also welded together. Obviously, outer shell [2 can be formed fromafgrea-ter or lesser number or sections} or can be cbnstruct'ed in any other desired'manner. 'T T An inlet manifold ring M for supplying the pro pellant-coolant to the annular passage is provided at the outer end of the thrust nozzle, and an outlet manifold ring I 8 for collecting the propellant-coolant after it has passed through said passage is provided at the combustion chamberend of the thrust cylinder. Inlet manifold M is attached to the thrust nozzle by having one of its sides welded to the larger diameter end of section [0d and have its other side welded to the large diameter end 0f-section 12d. Outlet manifold IB is attached to theithrust cylinder by having one of its sides welded to section We and its other side welded to one side of flanged ring 18. The other side of flanged ring I8 is welded to the endof section 10a. It will thus be seen that manifold ring [4 forms a closure for one end ofanannularpassage around inner shell l0 and also provides a means of ingress into said passage for the'coolant-propellant, and that manifold ring l6lforms a closure for the other end of said-passage and also provides a means of egress for said coolant-propellant.

Inner and outer shells i0 and 12 respectively are-formed from a material capable of withstanding the corrosive action of the propellant or propellants employed and/or their products of combustion and which is capable of being weld- :ed. Tomanufacture arocket motor thrust .cylinder capable of using gasoline. and nitric; acid as components of a bipropellant combination it is preferred to usea' material known as A. I. S. I. Type 3.47 stainless steel. This, is a material comprising the following analysis:

--in the art that other materials may be used which are" capable of being-welded and which have the necessary'high temperature strength and resistance to corrosion.

-Pipes 20 and Ham connected to inlet manifold I4 and outlet manifold I6 respectively and.

serve to supply inlet manifold M with propellant- -coolant from tank 32 and-to draw said propellantcoolant from outlet manifold [6. Pipe 22 is adapted to be connected to injector 34 carried by "an end plate 36 by means of a pipe 38. End plate 36 can be attachedito the thrustcylinder by being clamped to flanged ring l8. Injector 34 may be of any convenient design.-

Theannular space between inner shell 10 and outer shell I2 is extremely small relative to the diameter of the thrust cylinder-and the volume of coolant that imust pass therethrough, and should be *r'n'aintained .toclose tolerances if the highest possiblecoolant efficiencyis to be obtained; Also, inasmuch as both-inner shell l0 and; outer shell 12 are made up of relatively thin material, itis' necessary that inner shell [0, which is subjected to the extremely high temperature in operation,gand even when efiiciently and ade- -quat ely;:cooled sulfers -aconsiderable reduction in its modulus of elasticity, be reinforced to prevent it .from collapsing under- -thepressure of the coolant .in-the annular passageb-To both space inner and outer shells l0 and [2 a predetermined distance from each other and to reinforce inner shell l0,.a plurality of protuberances 24 are pressed inwardly from outer shell [2 a distance sufiicient to; give "them a height equal to tne r d erm n snaqe qs sdb tw shel s l0 and 12. Each protuberance is fastened to inner shell l0, preferably by spot welding and, inasmuch as it is desirable that there be a good thermal bond between each protuberance and inner shell Iii, each spot weld covers about 80% of the area of the face of the protuberance. It will thus be seen that protuberances 24, when spaced circumferentially and longitudinally along outer shell it, will space inner shell ii) a predetermined desired distance from said outer shell 12. Preferably, protuberances 26 are formed in shell l2 in a plurality of circumferential rings, each ring having its protuberances in adjacent circumferential rings. it is essential that sufficient protuberances 24 be provided and that they be spaced close enough together so that they will reinforce inner shell it when the thrust cylinder is in operation to prevent any collapse thereof. It is also equally important that no more protuberances be provided than are necessary to reinforce inner shell iii, inasmuch as too many protuberances cut down the cross sectional area of the annular passage which available for the coolant to flow through, thus making it increasingly difficult for the limited supply of coolant to successfully cool inner shell iii. The size of the protuberances is selected to provide a maximum amount of reinforcement and at the same time not unduly restrict the flow of coolant in the annular passage. The protuberances also serve as turbulence producing means in said annular passage and thus improve the ieat transfer from inner shell in to the propellant coolant.

The portion of the thrust cylinder which is subjected to the highest temperature is the most restricted portion of the thrust nozzle, i. e. torus section file. To permit the greater amount of heat which must be dissipated through torus section lilo to pass therethrough and be transferred to the propellant-coolant in the annular passage, it is preferred to make torus section Hie thinner than the other sections comprising inner shell 18. Inasmuch as torus section me is made of thinner material, its resistance to collapse from the fluid pressure of the propellant-cooiant is lower than the resistance of the other three sections and it is, therefore, necessary to provide torus section i2c of outer shell I 2 with more closely spaced protuberances. However, to avoid the loss of too much cross sectional area in the annular passage at this point, the protnberances formed in section 120 are of smaller diameter than the protuberances formed in the other sec tions of outer shell it. Obviously the entire inner shell H} can be made the same thickness as torus section l to.

berances in sections Etc, 522) and lZc to provide the increased reinforcement required.

A specific example of a rocket motor thrust cylinder incorporating the principles of the present invention, which has successfully operated continuously over extended periods of time, and which is adapted to use gasoline and nitric acid as components of a bipropellant combination, follows:

Section Ilia is a cylinder having a diameter However, when this is done it will be necessary to increase the number of protu id. Sections Ina, lflb and IBcZ preferably have a thickness of about .141 inch. Torus section lflc preferably has a thickness of about .078 inch. 'All four sections, Ilia, lllb, I00 and Hid are fabricated by rolling a sheet of material to the desired size and shape and welding the abutting edges together. Outer shell l2 has dimensions generally similar to those for inner shell ill but is sufliciently larger to permit the desired cross sectional area in the annular passage between. the two shells, and each section thereof preferably made in two halves to facilitate its assembly over inner shell iii. The two halves of the sections comprising outer shell i2, and the sections themselves, are preferably welded together by means of strap welds. The outer shell ii of a thrust cylinder for a rocket motor of the size of the example being given is suiiiciently larger in diam-- eter than inner shell iii to give an annular passage having a radial spacing in the order of .03 inch to .04 inch.

The radial spacing of shells ill and 12 of about .03 inch to .04 inch provides a thin layer of coolover over inner shell it that, while not a film, is a close approximation of a film as far as heat transfer characteristics of the coolant are concerned, and also is a spacing that is possible to attain in a practical Way within the limits of normal machine tools. Such a spacing also permits the propellant-coolant to flow therethrough without too great a pressure drop between inlet manifold M and outlet manifold I6.

The annular rings of protuberances 2d are spaced along cylindrical section lzc about 1%; inches apart. The protuberances 0n conical sections iflb and 52d are spaced progressively closer together, extending from the larger diameter ends to the smaller diameter ends of said conical sections, from about 1 inches apart extending down to spacing of about ,44 of an inch. The longitudinal spacing of the rings of protuberances on torus section iZc is about A of an inch. The number of protuberances 24 that make up each ring of protuberances along outer shell II. is the same in each ring regardless of the section upon which it appears, and preferably 20 protuberances are formed in each ring. The protuberances formed in sections 572a, l2?) and lid are all substantially .20 inch in diameter. The protuherances formed in tor .3 section 20 all have a diameter of approximatay .10 inch. All of the.

protuberances, regardless of the section on which they extend from the inner surface of outer shell iEa a distance in the order of .03 inch to .04 inch. Each of the protuberances is Welded to the adjacent portion of inner shell Hi to sec rely fasten the two shells together.

. Thrust cylinders, incorporating the principles of the present inven 1, having higher or lower thrust characteristics, ay be mad by proportionally increasing or decreasing the dimensions of the above described components.

Figure 5 illustrates a modified, form of the present invention whore-in plurality of holes 26 are formed in outer shell tile, and the edges of these holes are shaped to a rim or flange 28 around the holes. Flange 28 extends inwardly from the inner surface of outer shell its a distance su. stantially equal to the distance protubers-noes 2 lextend inwardly from outer shell i2. Outer shell 222 is attached to inner shell ice by filling holes with weld material til.

Since certain changes may be made in the above apparatus without departing from the scope of the invention herein involved, it is intended that all matter contained in the above dee7 scriptiomom or n inrt ezac oinpenyins d aw n :shall: rbev interpr ted as illustra ive nd n :in'a 'szlimit nesense.:;q za z- 1 at-=is claimed-is, l

Ayregeneratively cooled;,roclset.motor thrust ir v inder c p sinetaninner; s l nin a combustion portion and a thrust nozzle, an outer shell substantially enclosing and: concentrically spaced around said innerpshell to provide an an- :nular passage' for a coolant between said shells,

: .S iid shells being of relatively thin sheet material,:

tub lar and su stant a y n tary, sa d passa =.ext e nd;ing over said thrust nozzle and said combustien portion,said outer-shell being spaced substantially thesame distance from said inner shell throughoutits,lengthand joined thereto, apluvralityof spacing; and reinforcing protuberances pressed froxn-one -;of said shells and extending ,;across said-:annula-r, passage, and contacting the other ofrsaid shells; for-maintaining theradial spacing of said" shells, and providing means for join-ing them together, and inlet and outlet means for said passage-connecting .sa-id shells at their .adj-acenten;ds.-r: :2 r 3.- A regenerativelycooled rocket motor thrust cylinder comprisinganinnertubular shell defining acombustionportion and a thrust nozzle, :I'En outer tubular shell-substantiallyenclosing and concentrically spaced around'said inner shell to provide an-annular passage for a coolant between said rshells, said shells being of relatively thin sheet material, and substantially tubular, said passageextending over said thrust nozzle and said combustion portion, said outer shell being spacedsubstantially the same distance from said inner shell throughoutits length, a plurality of circumferentially and longitudinally spaced rein-forcingand spacing protuberances pressed from said outer shell and extending across said annular passage and contacting and fastened to said. inner shell to space and reinforce said inner shell a predeterminedudistance from said outer shell, and means for the ingress and egres of a coolant joining said innerand outer shells at theiradja- .ce ntedgesi, 1;. 1 r; .r l l r A r-e'generativelycooled rocket motor thrust cylinder" "adapted to be cooled-by the propellant employed to drivesaid motor comprising, an inner shell and an-outer shell substantially enclosing and concentrically spaced around said to :=*l ermi;t wheat. :-to be transferred through said inner shell to said propellant at a rate sufii- .cient to. maintain saidinnershell at: a safe temperature, andmeans defining the inlet andthe outletjor said-passageconnecting said inner and outer shells at their adjacent edges.

"-5; A regeneratively cooled rocket motorthrust cylinder adapted to consume a propellant'at a predetermined rate and adapted to be cooled by said propellant prior to its consumptionto permit said motor to'be operated continuously over extended periods of time comprising, an inner shell -defining .a combustion portion in which said propellant is-consumed-. and, an axially aligned -venturi-- thrust nozzle through which the hot products ofcombustion pass, an outer shell substantially: enclosing and concentrically spaced aroundr-and reinforcing said inner shell; and

forming with said inner shell an annular passage between said shells for said propellant, said transferred through said inner shell to said propellant at a rate sufficientto-maintain saidinner shell ata safe, temperature, and means for conducting saidpropellantto and away from said passagejoining theadjacentedges of said inner and outer shells. i

6;--A' light weight combustion device adapted to operate-continuously over extended periods of time and; to consume, at a predetermined rate, afluid supplied'it under pressure to thereby develop a'largevolume of gas at a high temperature comprising, a fabricated inner tubular shell having relatively thin walls defining a combustion portion and an exhaust-portion through which the products of-combustion pass, a relatively thin walled fabricated tubular casing for said shell concentrically spaced therearound to provide an annular passage between said shell and said casing-capable of conducting said fluid under pressure over-said shell prior to its entry into said combustion portion to cool said shell, a plurality of longitudinally and radially spaced protuberances formed from said casing extending across said passage and fastened to said inner shell to maintain the uniform spacing between said casdng andasaid inner shell, all of said protuberances beingsubstantially equal in length, said length inner shell to provide an annular passage for said propellant between "said shells, said shells being of relatively thinsheetfmaterial, tubular and substantially unitary," afplurality of spacing and rei'nforcing protuberances "pressed from one of said ishell's and engagingand'iastened to the other of -said shells, for maintaining a uniform cross-sectional area for said annular passage, the height of said protuberances bein such that the space betwirens'aid's hells will cause said propellant passing through said tassagegts ap rgiiiimate a film"passihg are engineer shellat' a velocity sufilciently being such thatthe cross sectional area of said annular passage-is-so proportioned to the periphery .-.of-said innershell and to the rate of flow of .said fluid that said fluid will be forced to flow through said annular passage in an approximation ofai'llm at a velocity which will permit heat 'to;lie-transferred through said inner shell to said 'fiuid atarate suflicient'to maintain said inner employed to drive said motor comprising, aninner shell and an outer shell concentrically spaced around said inner shell and substantially coextensive therewith to provide an annular passage for said propellant between said shells, said shells being of relatively thin sheet material, tubular and substantially unitary, a plurality of spacing and reinforcing protuberances pressed from one of said shells engaging and fastened to the other of said shells, the height of said protuberances being in the order of .03 inch to .04 inch to space said shells apart a distance in the order of .03 inch to .04 inch, whereby the space between said shells will cause said propellant passing therethrough to approximate a film passing over said inner shell at a velocity sufficiently high to permit heat to be transferred through said inner shell to said propellant at a rate sufficient to maintain said inner shell at a 10 safe temperature, and means uniting adjacent edges of said shells for furnishing said propellant to said passage and conducting the same away.

DAVID B. ROSSHEIM.

DOUGLAS V. DO ANE. CARLETON A. SIEMER.

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